Distribution of bacterial subgroups in the cecum content and fecal pellets of mice exposed for 8 weeks to Cd (20 or 100 mg L
) or Pb (100 or 500 mg L
) salts via their drinking water. (A) Family-level and (B) genus-level. 16S rRNA-base analyses were derived from 454/Roche multitag pyrosequencing. Data are expressed as the mean percentage abundance (n = 5 animals per group). Only operational taxonomic units (OTU’s) present in dominant families (> 0.1%) were considered. *: p < 0.05 and **: p < 0.01: significantly different from the control group (water with no added Cd or Pb) for the corresponding taxa. The color code is defined in the inset on the right of the Figure.